Bump joining method

ABSTRACT

The present invention provides a bump-joining apparatus, a bump-joining method, and a semiconductor component-manufacturing apparatus whereby bumps and electrode portions of circuit board are perfectly joined with higher join strength than in the conventional art. The apparatus includes a vibration generation device, a pressing device and a control unit, wherein bumps are pressed to electrode portions of a circuit board and vibrated with ultrasonic waves after reaching an initial contact area before reaching a join-completed-contact area at a completion of the joining, so that the bumps are more perfectly joined to the electrode portion than in the conventional art which vibrates the bump only after reaching the join-completed-contact area. Larger join strength is achieved than in the conventional art.

[0001] This application is a Divisional application of Ser. No.09/964,404 filed Sep. 28, 2001 now allowed, which is a Divisionalapplication of Ser. No. 09/354,087, filed Jul. 15, 1999 now U.S. Pat.No. 6,321,973, issued Nov. 27, 2001.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to an apparatus and a method forjoining bumps formed at electrodes of an electronic component toelectrode portions on a circuit board, and a semiconductorcomponent-manufacturing apparatus provided with the bump-joiningapparatus.

[0003] In one way for electrically connecting and fixing electroniccomponents onto a circuit board, there is carried out a method wherebybumps formed at electrodes of an electronic component are joined toelectrode portions on a circuit board. For instance, a semiconductorcomponent-manufacturing apparatus 1 shown in FIG. 1 is used to executethe bump-joining method, which roughly comprises a component feedapparatus 2, a bonding stage 3, a component reversal apparatus 4, abump-joining apparatus 5 and a circuit board transfer apparatus 6.

[0004] The component feed apparatus 2 feeds semiconductor chips as anexample of the electronic components, and the circuit board transferapparatus 6 carries circuit boards in to and out from the semiconductorcomponent-manufacturing apparatus 1. The bonding stage 3, where one ofthe circuit boards carried in by the circuit board transfer apparatus 6is loaded to be subjected to the joining, can be moved in a Y-directionby a Y-axis robot 7. The bonding stage 3 heats the circuit board for thejoining of bumps. The component reversal apparatus 4 holding one of thesemiconductor chips supplied from the component feed apparatus 2 turnsthe semiconductor chip upside down so that bumps formed at electrodes ofthe semiconductor chip face the circuit board loaded on the bondingstage 3. The bump-joining apparatus 5 includes a holding device forholding the semiconductor chip, a Z-directional driving device 51 formoving the held semiconductor chip in a thicknesswise direction of thesemiconductor, and an ultrasonic vibration generation device 9 whichwill be detailed later. The bump-joining apparatus 5 is mounted to anX-axis robot 8 to be moved in an X-direction by the X-axis robot 8,receiving the semiconductor chip from the component reversal apparatus4, transferring the semiconductor chip to the bonding stage 3, drivingthe Z-axis driving device 51 thereby pressing the received and heldsemiconductor chip at a predetermined position of the circuit boardloaded on the bonding stage 3 to join the bumps. A positioning of thesemiconductor chip to be joined onto the circuit board is carried out bythe X-axis robot 8 and Y-axis robot 7.

[0005] The bump-joining apparatus 5 is provided with the ultrasonicvibration generation device 9 which vibrates the bumps in the Y- orX-direction thereby generating heat of friction between the bumps andelectrode portions on the circuit board to decrease a heatingtemperature of the bonding stage and steady the joining of the bumps.The ultrasonic vibration generation device 9 has, as shown in FIG. 12, aplurality of layered piezoelectric elements 91 and an ultrasonic horn 92connected to one end portion of the piezoelectric elements 91. Avibration, e.g., in the Y-direction brought about when a voltage isimpressed to the piezoelectric elements 91 is amplified by theultrasonic horn 92. A nozzle 93 for holding of the semiconductor chip isfixed at the other end portion of the ultrasonic horn 92. The vibrationof the piezoelectric elements 91 brings about ultrasonic vibration tothe nozzle 93, i.e., semiconductor chip held by the nozzle 93. Althoughthe piezoelectric elements 91 vibrate in the Y-direction in FIG. 12,while the vibration is conducted to the semiconductor chip, vibrationsmoving in various directions also occur. Consequently the semiconductorchip is actually vibrated in various directions although primarilyvibrated in the Y-direction.

[0006] The conventional semiconductor component-manufacturing apparatus1 constituted as above joins the bumps in a manner describedhereinbelow.

[0007] The circuit board carried in by the circuit board transferapparatus 6 is loaded and heated on the bonding stage 3. In themeantime, the semiconductor chip held by the component reversalapparatus 4 from the component feed apparatus 2 is moved by thebump-joining apparatus 5 to a mount position on the bonding stage 3.Each of bumps 11 before being joined has a configuration, for example,as shown in FIG. 13. Specifically, a diameter I of each bump 11 isapproximately 100 μm, a height III of a base portion 11 a isapproximately 30-35 μm and a total height II of each bump 11 isapproximately 70-75 μm.

[0008] Each bump 11 of the configuration is pressed to each electrodeportion on the circuit board by the operation of the Z-directionaldriving device 51, pressed down as indicated in FIG. 14 and joined. Aheight IV of the bump 11 in FIG. 14 when pressed is nearly equal to theheight III of the base portion 11 a.

[0009] In the conventional semiconductor component-manufacturingapparatus 1, after the bump 11 is pressed in a state of FIG. 14 (whichwill be denoted by a reference numeral 12 hereinafter), the ultrasonicvibration generation device 9 is operated to vibrate each bump 12 withultrasonic waves and join the pressed bump 12 to each electrode portionof the circuit board.

[0010] According to the conventional art described above, eachcontact-area between each bump 12 and each electrode portion 21 of thecircuit board 20 is large because each bump 12 is started to be vibratedonly after each bump 11 is pressed to be formed as the bump 12 in FIG.14. In consequence, a sufficient scrub or friction cannot be attained insome cases between the bump 12 and electrode portion 21, resulting ininsufficiency of heat of friction necessary for the joining between thebump 12 and the electrode portion 21. The bump 12 and the electrodeportion 21 cannot be joined perfectly, with a resultant decrease in thejoin strength.

SUMMARY OF THE INVENTION

[0011] The present invention is devised to eliminate the above-discusseddisadvantage and has for its object to provide an apparatus and a methodfor perfectly joining bumps and electrode portions of a circuit boardwith larger joint strength than in the conventional art, and asemiconductor component-manufacturing apparatus including thebump-joining apparatus.

[0012] In accomplishing this and other objects, according to a firstaspect of the present invention, there is provided a bump-joiningapparatus for joining bumps formed at an electronic component toelectrode portions on a circuit board, which comprises:

[0013] a vibration generation device for generating relative vibrationsbetween the bumps and the electrode portions, with the bumps facing theelectrode portions;

[0014] a pressing device for moving the electronic component and thecircuit board relative to each other in a direction to bring the bumpsand the electrode portions close to each other, and pressing the bumpsof the electronic component and the electrode portions to each other, soas to compress the bumps; and

[0015] a control unit for controlling the pressing device to execute apressing action control to change a contact-area of each of the bumps toeach of the electrode portions through the compressing from an initialcontact area corresponding to each of the bumps to ajoin-completed-contact area corresponding to each of the bumps at thecompletion of the joining which exceeds the initial contact area, andfor controlling the vibration generation device to execute a vibrationcontrol to generate constant vibration from a time when the contact-areareaches the initial contact area to a time when the contact-area reachesthe join-completed-contact area.

[0016] According to a second aspect of the present invention, there isprovided a bump-joining method for joining bumps formed at an electroniccomponent to electrode portions on a circuit board, which comprises:

[0017] with the bumps facing the electrode portions, performing apressing operation to press the bumps and the electrode portionsrelatively so as to compress the bumps so that contact-areas between thebumps and the electrode portions change from initial contact areas tojoin-completed-contact areas at completion of the joining, with thejoin-completed-contact areas exceeding the initial contact areas; and

[0018] generating a constant (i.e., substantially unchanging,invariable, or uniform) vibration relatively between the bumps and theelectrode portions continuously (i.e., uninterrupted) from a time whenthe contact-area reaches the initial contact area to a time when thecontact-area reaches the join-completed-contact area, to thereby jointhe bumps to the electrode portions.

[0019] A semiconductor component-manufacturing apparatus according to athird aspect of the present invention features the above bump-joiningapparatus of the first aspect.

[0020] According to a fourth aspect of the present invention, there isprovided a bump-joining apparatus for joining bumps formed at anelectronic component to electrode portions on a circuit board, whichcomprises:

[0021] a vibration generation device for generating relative vibrationbetween the bumps and the electrode portions, with the bumps facing theelectrode portions;

[0022] a pressing device for moving the electronic component and thecircuit board relative to each other in a direction to bring the bumpsand the electrode portions close to each other, and pressing the bumpsof the electronic component and the electrode portions to each other, soas to compress the bumps; and

[0023] a control unit for controlling the vibration generation deviceand the pressing device to generate vibration before the bumps come intouch with the electrode portions until a contact-area of each of thebumps to each of the electrode portions reaches a join-completed-contactarea at completion of the joining.

[0024] According to a fifth aspect of the present invention, there isprovided a bump-joining method for joining bumps formed at an electroniccomponent to electrode portions on a circuit board, which comprises:

[0025] with the bumps and electrode portions facing each other,performing a pressing operation to press the bumps and the electrodeportions to each other relatively so as to compress the bumps so thatcontact-areas of the bumps to the electrode portions change tojoin-completed-contact areas at completion of the joining, wherein thejoin-completed contact areas exceed initial contact areas;

[0026] generating initial relative vibration between the bumps and theelectrode portions, without causing misregistration of the bumps and theelectrode portions, before the bumps come in contact with the electrodeportions and until the contact-areas reach the initial contact areas;and

[0027] generating constant (i.e., substantially unchanging, invariableor uniform) relative vibration, exceeding the initial vibration, betweenthe bumps and the electrode portions continuously (i.e., uninterrupted)from a time when the contact-areas reach the initial contact-areas to atime when the contact-areas reach the join-completed contact areas, soas to join the bumps to the electrode portions.

[0028] In the bump-joining apparatus according to the first aspect ofthe present invention and the bump-joining method according to thesecond aspect of the present invention, the vibration generation device,the pressing device and the control unit are provided, and the electrodeportions and the bumps are vibrated relatively from a time when each ofthe bumps obtains the initial contact area subsequent to the pressing toa time when the initial contact area changes to thejoin-completed-contact area. In comparison with the conventional artwherein the vibration is applied only after the join-completed-contactarea is attained, the vibration in these aspects of the presentinvention effectively works to generate the heat of friction from thetime when each contact-area between the bumps and the electrode portionsis small. So, each of the bumps is joined at an increased contact-areato each of the electrode portions. The bumps and the electrode portionsare perfectly joined throughout changing of the contact-area of each ofthe bumps to each of the electrode portions when the contact-areabecomes the join-completed-contact area. Thus larger joint strength isachieved relative the conventional art.

[0029] The semiconductor component-manufacturing apparatus according tothe third aspect of the present invention comprises the bump-joiningapparatus and the bump-joining method according to the first and secondaspects of the present invention, whereby the electronic component andthe circuit board of a produced semiconductor component are joined withlarger strength than in the conventional art.

[0030] According to the bump-joining apparatus of the fourth aspect ofthe present invention, the bumps and the electrode portions are vibratedrelatively before coming in contact with each other. Even when the bumpsare nonuniform in height, the bumps can be surely joined to theelectrode portions from the time when the bumps and the electrodeportions come in contact with each other. Moreover, a time required forsetting to achieve the initial contact area can be saved andconsequently the Tact time is shortened.

[0031] In the bump-joining method according to the fifth aspect of thepresent invention, the vibration relatively applied to the bumps and theelectrode portions is adapted to change in two levels, with the sameeffect as achieved by the bump-joining apparatus of the fourth aspect.The initial vibration is smaller than the vibration in the period fromthe initial contact area to the join-completed-contact area, thusdecreasing the possibility that the holding of the electronic componentis lost before the bumps and electrode portions are brought in contactwith each other.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] These and other aspects and features of the present inventionwill become clear from the following description taken in conjunctionwith the preferred embodiment thereof with reference to the accompanyingdrawings, in which:

[0033]FIG. 1 is a perspective view of an example of a semiconductorcomponent-manufacturing apparatus of an embodiment of the presentinvention;

[0034]FIG. 2 is an enlarged perspective view of a portion of abump-joining apparatus in the semiconductor component-manufacturingapparatus of FIG. 1;

[0035]FIG. 3 is an enlarged perspective view of a portion of a bondingstage in FIG. 1;

[0036]FIG. 4 is a diagram showing a state where a bump pressed by thebump-joining apparatus of FIG. 1 reaches an initial contact area;

[0037]FIG. 5 is a graph of an example of control of a bump joiningoperation carried out by the semiconductor component-manufacturingapparatus of FIG. 1;

[0038]FIG. 6 is a flow chart of a bump-joining method carried out by thesemiconductor component-manufacturing apparatus of FIG. 1;

[0039]FIG. 7 is a graph of another example of control of the bumpjoining operation carried out by the semiconductorcomponent-manufacturing apparatus of FIG. 1;

[0040]FIG. 8 is a diagram showing a different example of thebump-joining apparatus of FIG. 1;

[0041]FIG. 9 is a diagram showing a different example of thesemiconductor component-manufacturing apparatus of FIG. 1, specificallyin the periphery of the bump-joining apparatus and bonding stage;

[0042]FIG. 10 is a diagram of the bump in a different shape;

[0043]FIG. 11 is a perspective view of an example of a conventionalsemiconductor component-manufacturing apparatus;

[0044]FIG. 12 is a diagram of a holding portion for semiconductor chipsand a vibration generation device in the bump-joining apparatus;

[0045]FIG. 13 is a diagram of a shape of the bump formed at anelectronic component; and

[0046]FIG. 14 is a diagram of the pressed bump when reaching ajoin-completed-contact area at the completion of the joining.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] A bump-joining apparatus, a bump-joining method carried out bythe bump-joining apparatus, and a semiconductor component-manufacturingapparatus including the bump-joining apparatus according to a preferredembodiment of the present invention will be described hereinbelow withreference to the drawings throughout which like portions are designatedby like reference numerals.

[0048] In the embodiment to be described below, a semiconductor chipobtained by the following method is exemplified as the “electroniccomponent” mentioned in the foregoing “SUMMARY OF THE INVENTION”. Bumpsare formed at electrodes of integrated circuits formed on a semiconductor substrate such as a silicon wafer or the like, and then theintegrated circuits are split individually, whereby the semiconductorchips are obtained. The electronic component is not limited to thesemiconductor chip, and can be, for instance, a semiconductor componentsealing the semiconductor chip with resin and having bumps formed onelectrodes of the semiconductor component.

[0049] An ultrasonic vibration generation device 9 set at a bump-joiningapparatus 105 and including piezoelectric elements 91 in the embodimentcorresponds to the “vibration generation device” of the “SUMMARY OF THEINVENTION”, but is not limited to this.

[0050] Regarding the vibration, it is not restricted to the ultrasonicvibration and any kind of ultrasonic vibration is possible thatgenerates heat of friction between each of the bumps and each electrodeportion of a circuit board corresponding to each bump, therebydecreasing a heating temperature of a bonding stage for the circuitboard. Although the ultrasonic vibration changes depending on conditionssuch as a size of the semiconductor chip, the number of bumps, etc., thevibration may be used, for example, with an amplitude of approximately0.5 μm.

[0051] The function of the “pressing device” described in the “SUMMARYOF THE INVENTION” is achieved by a voice coil motor 121 installed at thebump-joining apparatus 105 according to the embodiment. The “pressingdevice” is not necessarily the voice coil motor.

[0052] As is apparent from FIG. 1, a semiconductorcomponent-manufacturing apparatus 101 according to the embodiment of thepresent invention is not different in structure from most of thesemiconductor component-manufacturing apparatus 1 described earlier. Thesemiconductor component-manufacturing apparatus 101 typically features acontrol unit 110 which realizes a bump-joining method to be described indetail later. Specifically, the semiconductor component-manufacturingapparatus 101 roughly comprises a component feed apparatus 102, abonding stage 103, a component reversal apparatus 104, the bump-joiningapparatus 105, a circuit board transfer apparatus 106, and the controlunit 110. The component feed apparatus 102 corresponds to theabove-described conventional component feed apparatus 2. The bondingstage 103 corresponds to the conventional bonding stage 3. The componentreversal apparatus 104 corresponds to the conventional componentreversal apparatus 4. The bump-joining apparatus 105 corresponds to theconventional bump-joining apparatus 5. The circuit board transferapparatus 106 corresponds to the conventional circuit board transferapparatus 6. Here the detailed description for the component feedapparatus 102, bonding stage 103, component reversal apparatus 104,bump-joining apparatus 105, and circuit board transfer apparatus 106will therefore be omitted except for the following supplementarydescription.

[0053] To the component feed apparatus 102 are supplied from a magazinelifter 111 a semiconductor wafer 112 of a state in which individualintegrated circuits are scribed with having bumps formed at electrodesof the individual integrated circuits of the semiconductor wafer 112.The component feed apparatus 102 stretches the wafer 112 and divides thewafer into semiconductor chips. A wafer recognition apparatus 113 setabove the component feed apparatus 102 picks up images of states of thewafer 112 supplied to the component feed apparatus 102 and individualsemiconductor chips, and feeds information of the picked-up images tothe control unit 110. Although the component feed apparatus 102 in theembodiment is constituted in the form described above because thesemiconductor chip is exemplified as the electronic component, thecomponent feed apparatus is changed into a different form if theelectronic component to be processed is a different kind.

[0054] Naturally, a circuit formation portion of the wafer 112 with thebumps is faced upward. A plunging device 120 of the component feedapparatus 102 plunges up each of the divided semiconductor chips in itsthicknesswise direction. The component reversal apparatus 104 holds thechips one by one and turns each chip upside down so that the bumps facethe electrode portions 21 of the circuit board 20.

[0055] In the embodiment, the wafer 112 has a base formed of LiTaO₃,LiNbO₃ or the like ferroelectric body, and the bump is formed of gold.

[0056] The bonding stage 103 is constructed in a ball screw structure asindicated in FIG. 3. The bonding stage 103 is slid in a Y-direction by aY-axis robot 107, having a motor 114 as a driving unit. For enabling thecircuit board 20 to be loaded on the bonding stage 103, in other words,for making the bonding stage 103 conform in size with the circuit board20 supplied from the circuit board transfer apparatus 106, the bondingstage 103 is equipped with a substrate regulation unit 115 which holdsan edge portion of the circuit board 20 in the Y-direction and can movein the X-direction, and a substrate regulation unit 116 which holds anedge portion of the circuit board 20 in the X-direction and can move inthe Y-direction. The bonding stage 103 has a suction path for suckingand holding the circuit board 20. The suction path communicates with asuction apparatus 117. A heating apparatus 118 is attached to thebonding stage 103 to heat the circuit board 20 to approximately 150° C.for joining the bumps.

[0057] The bump-joining apparatus 105 includes the ultrasonic vibrationgeneration device 9 and semiconductor chip-holding nozzle 93 set at alower end portion as depicted earlier with reference to FIG. 12. Stillreferring to FIG. 12, a suction path 94 is formed in the nozzle 93 alongwith an axial direction of the nozzle 93 to suck and hold thesemiconductor chip 150. The suction path 94 communicates with a suctionapparatus 119. The semiconductor chip 150 is held not necessarilythrough a suction action by the nozzle 93, and can be held, e.g., in amechanical way. In moving the semiconductor chip 150 in a direction(Z-direction in the embodiment) in which the bumps 11 and the electrodeportions 21 facing the bumps come close to each other as shown in FIG.12, thereby pressing the bumps 11 and the electrode portions 21 to jointhe bumps and the electrode portions 21 of the circuit board 20, at thistime, a driving device, specifically, the known voice coil motor (VCM)121 shown in FIG. 2 is used in the embodiment. The bump-joiningapparatus 105 is also equipped with a motor 122 for rotating the nozzle93 in a direction about an axis thereof.

[0058] The operation of the bump-joining apparatus 105 is controlled bythe control unit 110 which will be described later.

[0059] An X-axis robot 108 for moving the above bump-joining apparatus105 in the X-axis direction is of a ball screw structure in theembodiment as shown in FIG. 2, and has a motor 123 as a driving unit.

[0060] The control unit 10 is electrically connected to each of theabove-described apparatuses, for example, the component feed apparatus102, the bonding stage 103, the component reversal apparatus 104, thebump-joining apparatus 105 including the voice coil motor 121 and thepiezoelectric elements 91, and the circuit board transfer apparatus 106,etc., thereby controlling operations of these apparatus. In theembodiment, one control unit 110 is set for the entire semiconductorcomponent-manufacturing apparatus 101 to control, e.g., the bump-joiningoperation, etc. However, the control unit may be set corresponding toeach of the apparatuses, for instance, for the bump-joining apparatus105 to execute control of the bump join operation.

[0061] The control of the bump joining operation carried out by thecontrol unit 110 which characterizes the embodiment will be discussed indetail hereinbelow, while the control by the control unit 110 of theother apparatuses is omitted from the description because the control ofthe other apparatuses is equal to in the conventional art.

[0062] In the conventional art, only after the bumps 11 of FIG. 13 arepressed to the electrode portions 21 of the circuit board 20 and thuscompressed to form the bumps 12, of FIG. 14, the ultrasonic vibrationgeneration device 9 is operated to apply the ultrasonic vibration to thebump 12.

[0063] In contrast, according to the embodiment, the ultrasonicvibration generation device 9 is operated to apply the vibration of thedevice 9 to the bumps 11, 12 from a time point when the bumps 11 arepressed to the electrode portions 21 into a state shown in FIG. 4 to atime when the bumps 11 are turned into the bumps 12. This manner ofcontrol causes the ultrasonic vibration to act on the bumps 11, 12 whilechanging a contact-area of each of the bumps 11 with respect to each ofthe electrode portions 21. Thus, heat of friction resulting from theultrasonic vibration is applied to the bumps 11, 12 throughout thechanging of the contact-area, and accordingly the bumps 11, 12 areuniformly joined with the electrode portions 21. The bumps 12 can beintegrated with the electrode portions 21 all over the contact area morefirmly than in the conventional art.

[0064] The bump joining operation will be more fully depicted withreference to FIG. 6, etc.

[0065] The semiconductor chip 150 employed in the embodiment has 20bumps 11 of gold. The electrode portions 21 to which the bumps arepressed are formed of gold as well. When a current is supplied to thevoice coil motor 121, the nozzle 93 moves in the axial directionthereof, that is, the Z-direction which is equal to the thicknesswisedirection of the semiconductor chip 150 sucked and held by the nozzle93. In consequence, the bumps 11 of the semiconductor chip 150 arepressed to the electrode portions 21 of the circuit board 20.Information of a relationship of the current supplied to the voice coilmotor 121 and a pressing force of the bumps pressing the electrodeportions 21 subsequent to the supply of the current is stored in advancein the control unit 110. The control unit 110 obtains a load value ofthe pressing force from the current value fed to the voice coil motor121. The load value is obtained in a known manner corresponding to aform of the above relationship information, for instance, a table, anoperation formula, etc.

[0066] Specific values mentioned in the following description are basedon an example where each of 20 gold bumps of one semiconductor chip 150has a shape and a size described with reference to FIG. 13, andtherefore the values are changeable when these conditions change.

[0067] In step 1 (e.g. denoted by S1 in FIG. 6) in FIG. 6, the controlunit 110 controls operations of the X-axis robot 108 and Y-axis robot107, and disposes the bumps 11 to face the electrode portions 21 forjoining thereof. In step 2, the control unit 110 operates the voice coilmotor 121 to bring the bumps 11 into touch with the electrode portions21. The bumps and the electrode portions are started to be pressed instep 3, whereby the contact-area between each of the bumps 11 and eachof the electrode portions 21 changes. Each leading end portion 11 b ofthe bumps 11 is compressed as is clearly shown in FIG. 4. Thecontact-area of each bump 11 to each electrode portion 21, becomes aninitial contact area respectively in step 4. In the embodiment, a heightV in FIG. 4 is 60-65 μm and a diameter V1 of a portion of each initialcontact area is 5-10 μm.

[0068] That the bumps 11 touch the electrode portions 21 and that thecontact-areas of the bumps 11 reach the initial contact areas of thebumps 11 are detected by obtaining the aforementioned load value. Thatis, the control unit 110 detects the current value fed to the voice coilmotor 121 and obtains the load value from the current value on the basisof the above relationship information. As indicated in FIG. 5, accordingto the embodiment, the control unit 110 recognizes the touch or contactwhen detecting the load of 100 g with 20 bumps, and judges that theinitial contact areas are achieved when detecting the load of 300 g,i.e., 15 g per one bump 11. Since a tolerance of 150 g is set in theembodiment, the control unit 110 judges that the bumps 11 lead to theinitial contact areas when the load is included within a range of 300g±50 g.

[0069] According to the embodiment, the control unit 110 performs timecontrol so that the contact-areas change to the initial contact areas in0.1 sec after the bumps 11 touch the electrode portions 21.

[0070] At a time point when the contact-areas become the initial contactareas, in step 5, the control unit 110 applies a voltage to thepiezoelectric elements 91 of the ultrasonic vibration generation device9, thereby causing the ultrasonic vibration to act on the nozzle 93,i.e., bumps 11 of the semiconductor chip 150 as well as pressing thebumps 11. The generated ultrasonic vibration in the embodiment has afrequency of 60 kHz, whereby a semiconductor chip holding portion of thenozzle 93 is vibrated with an amplitude of 1-2 μm. The ultrasonicvibration to the bumps 11 is continued until step 7 to be describedlater. The ultrasonic vibration with the above frequency is continued ina constant manner during the time. In other words, a constant (definedherein to mean substantially unchanging, invariable, or uniform)relative vibration of 60 kHz between the bumps 11 and the electrodeportions 21 is generated continuously (defined herein to meanuninterrupted) from a time at which the contact areas of the bumps reachthe initial contact areas to a time at which the contact areas reachcompleted contact areas, so as to join the bumps to the electrodeportions.

[0071] The reason why the ultrasonic vibration is started from the timepoint when the contact-areas of the bumps 11 reach the initial contactareas of the bumps 11, not from a time point when the bumps 11 touch theelectrode portions 21 is as follows: If the bumps 11 are vibrated in astate in which they each have a sharp leading end portion 11 b as shownin FIG. 13, the bumps 11 and the electrode portions 21 are brought inpoint contact, causing the bumps 11 to loosely shift from the electrodeportions 21. So, joining positions of the bumps 11 may become unstable.More specifically, if the bumps 11 are vibrated with the above amplitudeof 1-2 μm with the leading end portions of the bumps 11 being pointed inshape, the bumps 11 slide with respect to the electrode portions 21. Asa result, a shift of not smaller than ±50 μm is introduced, although thebumps and the electrode portions are joined generally with an accuracyof ±15 μm with respect to a normal joining position.

[0072] Therefore, each initial contact area is a minimum area to preventthe positional shift i.e., misregistration between each bump 11 and eachelectrode portion 21. In a relationship between the initial contactareas and a magnitude of the ultrasonic vibration, for example, theinitial contact area of one bump 11 is approximately 30-40% the diameterof one bump 11 when the amplitude is 1 μm.

[0073] In step 6, the current is supplied to the voice coil motor 121 toapply the load to the bumps 11 so as to change each of the contact-areasto each of join-completed-contact areas (i.e. contact areas between thebumps and electrodes after completion of the joining thereof) atcompletion of the joining of the bumps 12 to the electrode portions 21as shown in FIG. 14. Each join-completed-contact area has an areaexceeding each initial contact area. In the embodiment, the load isapplied to the bumps 11 in step 6 with a constant rate of change asindicated in FIG. 5. The load when the contact-areas reach thejoin-completed-contact areas is 100 g per one bump, i.e., 2000 g intotal. The control unit 110 controls the pressing action so that ittakes 0.3 sec to achieve the join-completed-contact areas after thecontact-areas become the initial contact areas.

[0074] When the load becomes 2000 g, in other words, the contact-areasreach the join-completed-contact areas in step 7, the control unit 110terminates the pressing action of the bumps 12 to the electrode portions21 and at the same time terminates the ultrasonic vibration to the bumps12.

[0075] In the embodiment, the control unit 110 changes the load actingto the bumps 11 with the constant rate in step 6. However, the presentinvention is not limited to this arrangement; for instance, the load canbe changed in a quadratic curve as represented by a reference numeral140 in FIG. 7 or changed stepwise as indicated by a reference numeral141.

[0076] On the other hand, although the pressing force to the bumps 11 isdetected from the load value, in the embodiment, the present inventionis not confined to this. From a point of view of perfectly joining thebumps with the electrode portions 21 of the circuit board 20 which isthe aim of the present invention, it is ideal to join the bumps and theelectrode portions 21 surely in every state while the contact-areasincrease. Since the ultrasonic vibration is applied continuously to thebumps as described above in the embodiment, it is best that the currentto be supplied to the voice coil motor 121 is controlled to makeconstant an increase rate of the contact-areas. As such, information ofa relationship of the pressing force, namely, current and thecontact-areas is required to be supplied beforehand to the control unit110 to effect this type of control. The control unit 110 obtains thecontact-areas from the current value supplied to the voice coil motor121, thereby controlling the current to make the change rate of thecontact-areas constant, and thus controls the pressing force.

[0077] As shown in FIGS. 4 and 14, the bumps 11 are compressed by thepressing action, and the height of each bump 11 in a movement directionof the semiconductor chip 150 held by the nozzle 93 changes accordingly.Therefore, the current to be supplied to the voice coil motor 121 may becontrolled to make an increase rate of the height constant. For thiscontrol, the control unit 110 needs information of a relationship of thepressing force, i.e., current value and the height beforehand. Thecontrol unit 110 obtains the height from the current value supplied tothe voice coil motor 121, and controls the current to make the rate ofchange of the height constant, thereby controlling the pressing force.

[0078] The voice coil motor 121 is employed as a driving device to movethe semiconductor chip 150 in the embodiment. The driving device is notlimited to the voice coil motor and can be constituted of, e.g., a ballscrew structure 130 of FIG. 8 thereby moving the nozzle 93 by a motor131. The pressing force may be measured by a load cell 132 in this case.

[0079] The operation of the semiconductor component-manufacturingapparatus 101 in the above constitution will be described below.

[0080] The circuit board 20 is supplied to the bonding stage 103 by thecircuit board transfer apparatus 106, and heated while being sucked onthe bonding stage 103. In the 10 meantime, the wafer 112 is moved fromthe magazine lifter apparatus 111 and mounted to the component feedapparatus 102. The wafer 112 is stretched by the component feedapparatus 102. The component reversal apparatus 104 holds semiconductorchips 150 one by one from the component feed apparatus 102 and turnseach semiconductor chip 150 upside down. The X-axis robot 108 is thendriven to move the bump-joining apparatus 105 to a positioncorresponding to the component reversal apparatus 104. The tipped-oversemiconductor chip 150 is held by the nozzle 93 of the bump-joiningapparatus 105. After the holding, the X-axis robot 108 is driven againto move the bump-joining apparatus 105 to above the bonding stage 103.Then the X-axis robot 108 and Y-axis robot 107 are operated so that thebumps 11 of the semiconductor chip 150 and the electrode portions 21 ofthe circuit board are arranged to correspond to each other at a positionon the circuit board 120 held at the bonding stage 103 where thesemiconductor chip 150 is to be joined. The earlier-described joiningoperation is carried out thereafter, whereby the bumps 11 and electrodeportions 21 are joined.

[0081] After all semiconductor chips 150 are completely joined on thecircuit board 20, the bonding stage 103 is moved to the circuit boardtransfer apparatus 106 and the circuit board transfer apparatus 106 inturn transfers the circuit board 20 to the next process from the bondingstage 103.

[0082] According to the bump-joining apparatus and bump-joining methodof the foregoing embodiment, when the bumps 11 are pressed to theelectrode portions 21 of the circuit board 20, not only thecontact-areas of the bumps 11 to the electrode portions 21 change, butthe ultrasonic vibration acts on the bumps 11, 12. Therefore, the bumps11, 12 can be joined with the electrode portions 21 uniformly throughoutthe changing of the contact-areas of the bumps 11, 12 by the heat offriction generated from the ultrasonic vibration in addition to theheating by the bonding stage 103. The bumps 12 and electrode portions 21are joined more firmly than in the conventional art for the wholecontact-areas.

[0083] In the above embodiment, the bump-joining apparatus 105 is movedtowards the circuit board 20 to press the bumps 11 to the electrodeportions 21. The present invention is not limited to the embodiment. Forexample, a bump-joining apparatus 205 is fixed when bumps are joined tothe electrode portions, a bonding stage 203 and loading the circuitboard 20 may be moved to the bump-joining apparatus 205, as shown inFIG. 9. In such example, a voice coil motor 221 may be used as a drivingdevice to move the bonding stage. A movement amount of the bonding stagecan be controlled by the current supplied to the voice coil motor 221,similar to the above. In other words, the bump-joining apparatus and thebonding stage loading the circuit board 20 are moved relatively when thebumps are joined to the electrode portions. A reference numeral 207 inFIG. 9 indicates a Y-axis robot, and a reference numeral 208 is anX-axis robot.

[0084] Although the ultrasonic vibration is applied to the nozzle 93,the present invention is not restricted to this. Instead, the circuitboard 20 may be vibrated by an ultrasonic vibration generation device209. That is, the bumps 11 and circuit board 20 are vibrated relative toeach other.

[0085] In the embodiment, the bumps 11 are kept pressed by thebump-joining apparatus 105 to reach the initial contact area. Theinvention is not limited to this, and the semiconductor chip 150 or thelike electronic component preliminarily having the initial contact areasat the leading end portions 11 b of the bumps 11 may be sent to thesemiconductor component-manufacturing apparatus 101 or bump-joiningapparatus 105. In such arrangement, the pressing action and theultrasonic vibration are started from the time point when the bumps 11and electrode portions 21 come in contact with each other.

[0086] Each bump 11 formed at the semiconductor chip 150 is shaped asillustrated in FIG. 13 in the embodiment. Each bump 11 is not restrictedto this form and may, e.g., have a plurality of top portions 250 asshown in FIG. 10.

[0087] As described with reference to FIG. 5, according to the presentembodiment, the pressing action of the bumps 12 to the electrodeportions 21 is terminated and moreover the ultrasonic vibration to thebumps 12 is stopped simultaneously when the contact-areas between thebumps 11 and the electrode portions 21 become the join-completed-contactareas. That is because if the ultrasonic vibration to the bumps 12 iscontinued for a long time after the completion of the joining, thejoined portions sometimes break. For avoiding this, in the embodiment,the ultrasonic vibration is stopped within approximately 0.3 sec afterthe join-completed-contact areas are obtained.

[0088] It is not always necessary for the ultrasonic vibration to startat the time point when the contact-areas become the initial contactareas.

[0089] The nozzle 93 is vibrated relatively strongly with the amplitudeof 1-2 μm in the embodiment described above. Thus, before beingvibrated, the bumps 11 are compressed to attain the initial contactareas, thereby being prevented from shifting from the electrode portions21. On the other hand, in the case with no positional shift occurring,for example, when the nozzle is vibrated with a relatively smallamplitude of about 0.5 μm, the bumps 111 and electrode portions 21 maybe allowed to be vibrated relative to each other before coining incontact with each other. Even the vibration with the amplitude of 0.5 μmcan generate the heat of friction, ensuring good joining of the bumps11, 12 with the electrode portions 21.

[0090] The following effect is realized when the vibration is carriedout before the bumps 11 and electrode portions 21 come in contact witheach other. Supposing that three kinds of bumps 11, i.e., high, middle,and low bumps of the height 11 as shown in FIG. 13 are formed at thesemiconductor chip 150, and the ultrasonic vibration is started afterthe semiconductor chip 150 is pressed to compress the low bump to formthe initial contact area, the middle and high bumps are held in contactwith the electrode portions 21 with areas not smaller than the initialcontact areas of the middle and high bumps at this time. Therefore, themiddle and high bumps are harder to vibrate than the low bumps, possiblyresulting in insufficient joining at the start of the ultrasonicvibration. To the contrary, any of the low, middle and high bumps can bejoined well if the vibration is started before the bumps 11 andelectrode portions 21 are brought into contact with each other.

[0091] In order to eliminate the probability that the semiconductor chip150 is separated from the nozzle 93 when the vibration is carried outbefore the bumps 11 and electrode portions 21 are in contact with eachother, a Suction force for the semiconductor chip 150 is increased, afriction at a contact face between the semiconductor chip 150 and nozzle93 is strengthened or the like idea is required in some cases.

[0092] Further, an arrangement is adoptable whereby initial vibrationnot bringing about the positional shift is carried out before the bumps11 and electrode portions 21 come in contact with each other until thecontact-areas of the bumps 11 reach the initial contact areas of thebumps 11, and then constant vibration exceeding the initial vibration,for instance, with an amplitude of 1-2 μm described earlier is appliedafter the contact-areas become the initial contact areas until thecontact-areas reach the join-completed-contact areas of the bumps 12.Even the initial vibration produces the heat of friction, therebyenabling good joining of the bumps 11, 12 with the electrode portions21.

[0093] Through the above-discussed control of the vibration, thepositional shift is avoided and a time required for setting to achievethe initial contact areas is saved, so that a Tact time is shortened andperfect joining is accomplished. Moreover, the small initial vibrationsuppresses the danger of the separation of the semiconductor chip 150from the nozzle 93 even when the vibration is started before the bumps11 and electrode portions 21 are brought in contact with each other.

[0094] Although the present invention has been fully described inconnection with the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications are apparent to those skilled in the art. Such changes andmodifications are to be understood as included within the scope of thepresent invention as defined by the appended claims unless they departtherefrom.

What is claimed is:
 1. A bump-joining apparatus for joining bumps formedat an electronic component to electrode portions on a circuit board,which comprises: a vibration generation device for vibrating the bumpsof the electronic component having the bumps faced to the electrodeportions and the electrode portions relatively for the joining; apressing device for moving the electronic component and the circuitboard relatively in a direction to bring the bumps and the electrodeportions close to each other, and pressing the bumps of the electroniccomponent and the electrode portions to each other, so as to compressthe bumps; and a control unit for controlling the vibration generationdevice and the pressing device in operation, which executes a pressingaction control to the pressing device to change a contact-areacorresponding to each of the bumps to each of the electrode portionsthrough the compressing from an initial contact area corresponding toeach of the bumps to join-completed-contact area corresponding to eachof the bumps at the completion of the joining which exceeds the initialcontact area, and a vibration control to the vibration generation deviceto generate constant vibration from a time when the contact-area reachesthe initial contact area to a time when the contact-area reaches thejoin-completed-contact area.
 2. A bump-joining apparatus according toclaim 1, wherein the pressing action control by the control unit to thepressing device is carried out to attain a constant rate of change ofthe contact-area from the initial contact area to thejoin-completed-contact area.
 3. A bump-joining apparatus according toclaim 2, wherein the control unit executes the pressing action controlwith the constant rate of change of the contact-area on a basis of apressing force-vs.-area information showing a relationship between thepressing force generated by the pressing device and the contact-area. 4.A bump-joining apparatus according to claim 1, wherein the pressingaction control by the control unit to the pressing device is carried outto attain a constant rate of change of a load required for the pressingwhile the contact-area changes from the initial contact area to thejoin-completed-contact area.
 5. A bump-joining apparatus according toclaim 4, wherein the control unit executes the pressing action controlwith the constant rate of change of the load on a basis of the pressingforce-vs.-load information indicating a relationship between thepressing force generated by the pressing device and the load.
 6. Abump-joining apparatus according to claim 1, wherein the pressing actioncontrol by the control unit to the pressing device is carried out toattain a constant rate of change of a height of each of the bumps in thedirection to bring the bumps and the electrode portions close to eachother while the contact-area changes from the initial contact area tothe join-completed-contact area.
 7. A bump joining apparatus accordingto claim 6, wherein the control unit executes the pressing actioncontrol with the constant rate of change of the height on a basis of thepressing force-vs.-height information indicating a relationship betweenthe pressing force generated by the pressing device and the height.
 8. Abump-joining apparatus according to claim 1, wherein the initial contactarea is a minimum area not causing misregistration between each bump andeach electrode portion when the bump and the electrode portion are movedrelatively.
 9. A bump-joining apparatus according to claim 3, whereinthe pressing device is equipped with a motor, and the pressing force ischanged in accordance with a current fed to the motor.
 10. Abump-joining apparatus according to claim 1, wherein the relativevibration between the bumps and the electrode portions is achieved byvibrating the bumps without vibrating the circuit board, and therelative movement of the electronic component and the circuit board isachieved by moving the electronic component towards the circuit boardwithout moving the circuit board.
 11. A semiconductorcomponent-manufacturing apparatus comprising the bump-joining apparatusaccording to claim
 1. 12. A bump-joining apparatus for joining bumpsformed at an electronic component to electrode portions on a circuitboard, which comprises: a vibration generation device for vibrating thebumps of the electronic component having the bumps faced to theelectrode portions and the electrode portions relatively for thejoining; a pressing device for moving the electronic component and thecircuit board relatively in a direction to bring the bumps and theelectrode portions close to each other, and pressing the bumps of theelectronic component and the electrode portions to each other, so as tocompress the bumps; and a control unit for controlling the vibrationgeneration device and the pressing device in operation, which subjectsthe vibration generation device to vibration control to generate thevibration before the bumps come in touch with the electrode portionsuntil a contact-area corresponding to each of the bumps to each of theelectrode portions reaches a join-completed-contact area at completionof the joining.
 13. A bump-joining apparatus according to claim 12,wherein the control unit executes a pressing action control to thepressing device after the bumps come in touch with the electrodeportions to change, through the compressing, the contact-area of eachbump to each electrode portion via an initial contact area to thejoin-completed-contact area which exceeds the initial contact area; anda vibration control to the vibration generation device to generateinitial vibration not causing misregistration between the bumps andelectrode portions before the bumps come in touch with the electrodeportions until the contact-area reaches the initial contact area, andgenerate constant vibration exceeding the initial vibration from a timewhen the contact-area reaches the initial contact area to a time whenthe contact-area reaches the join-completed-contact area.